From
The Desk Of Clarence Bass

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Endurance and
resistance training are proving to be the dynamic duo that build and rejuvenate
the body from head to toe.

Strength Training Good for the Brain

We learned earlier that aerobic exercise reverses the brain
shrinkage that occurs in some older people:
http://cbass.com/AerobicsBrain.htm. We also saw that, in mice, aerobic
exercise generates brain-derived neurotrophic factor (BDNF). Harvard
psychiatrist John J. Ratey wrote about this “factor” in SPARK:The Revolutionary New Science of Exerciseand the Brain
(Little, Brown, 2008). He called BDNF “Miracle-Gro for the brain,” because it
“nourishes neurons [brain cells] like fertilizer.” When researchers sprinkle
BDNF on neurons in the lab, the cells spontaneously sprout new branches.

We haven’t seen much research on how strength training
affects the brain. (Ratey joked, “It’s difficult to get rats to pump iron.”)
We’re still not dissecting human brains after exercise, but we do have a new
study showing changes in circulating BDNF after intense resistance training.

Lead researcher Joshua Yarrow, PhD, post-doctoral associate
at the University of Florida (Gainesville) presented the study at the American
College of Sports Medicine 57th Annual Meeting in Baltimore, MD. The
presentation was reported online June 4, 2010, by Jennifer Monti in Medscape
Medical News.

While the study is subject to interpretation, it may
explain how resistance training (includes weight lifting) protects and improves
brain function.

Resistance Training Generates BDNF

Dr. Yarrow began by recalling that people who do regular
endurance training are less subject to neurodegenerative diseases, such as
Alzheimer’s disease.

Yarrow and his team evaluated the effect of strength
training on circulating brain-derived neurotrophic factor (BDNF), the
stimulating molecule. Again, Dr. Ratey called it “Miracle-Gro for the brain.”
(The medical dictionary definition of neurotrophic is “nourishing nerve
cells.” BDNF plays a role in the growth, development, maintenance, and function
of several neuronal systems.)

They recruited 20 college-aged men to test whether intense
resistance training increased circulating BDNF at 1, 30, and 60 minutes after
exercise. (We are not given specifics on the training.) Serum BDNF increased 32%
one minute after exercise, but returned to resting levels within 30 minutes, and
was 41% below resting 60 minutes after exercise.

Medscape reported Dr. Yarrow’s explanation: The
study reveals that resistance training induces a robust transient increase in
circulating BDNF. It has been shown that during endurance training, BDNF is
produced in the brain. But BDNF is produced in many tissues, including skeletal
muscle and the lining of heart, blood, and lymph vessels. The production of BDNF
outside the brain with resistance training, which might then affect the brain,
is important because we know that BDNF crosses the blood-brain barrier and can
act within the brain.

“Resistance exercise may essentially feed BDNF to the
brain, which is why we see an increase in circulating levels immediately post
exercise and then a decrease…within an hour,” Yarrow said.

“This is important because we may be able to say that
endurance exercise is not necessary for everyone who seeks the neuroprotective
benefits of exercise. We may be able to tailor resistance training programs to
optimize the exposure of neural tissue to neurotrophic factors like BDNF,” he
added. (It also helps to make the case for balanced training, strength and
endurance.)

Another Interpretation

J. Carson Smith, PhD, associate professor at the University
of Wisconsin, Milwaukee—it’s not clear whether he was directly involved in the
study—offered another interpretation of what happens to the BDNF that is
released after resistance training. “In addition to the possibility that the
BDNF circulates to the brain and crosses the blood-brain barrier to act in
target tissues in the brain, it is possible that the BDNF is released
peripherally and then is simply cleared from the circulation after a relatively
short amount of time.”

(If we can just persuade those stubborn rats to start
lifting, we can find out were the BDNF goes.)

Smith said these findings have implications for the
understanding of how both endurance and resistance exercise can lead to the
release of neuromodulators that optimize the function of the nervous system from
multiple perspectives. (Neuromodulators are substances that alter nerve
impulse transmission.)

Both researchers agree that BDNF can have positive effects
on cognition, mood, emotions, and other domains of brain function.

* * *

My amateur status allows me to postulate that BDNF protects
and improves nerve function all over the body. It appears that resistance
training has more positive benefits than imagined possible a few short years
ago. Endurance and resistance training are proving to be the dynamic duo that
build and rejuvenate the body from head to toe.